What dog gets used the most?

The number one dog used in dog fighting today in America is the American pit bull terrier. They are used because they are smaller than the bull terrier. Other dogs such as german Sheppard, and doberman pinschers were also used in fighting. Those dogs were reported to be "bait dogs" which those dogs train the other dogs to fight and become tougher. There is good information at http://www.aspca.org/fight-animal-cruelty/dog-fighting/dog-fighting-faq.html . There is a bunch of other info on that website as well. Like when dog fighting first came to America which was around the 1860s. Also it tells you where the dogs come from also the different levels of fighting such as street, hobbyist, and professionals. it tells you how the dogs were raised and trained. there is a bunch more things on that website so enjoy.